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Biol152 Exam #1 2012 Fall There is one best answer for each question. For any question in which a model system is altered from it normal functioning. Assume that only the stated change differs from the model and that all other parts of the system act as they usually do. Membrane potential of an axon during the resting stage and during an action potential. Refer to the structures below and the graph above to answer questions 1 to 4. i. leak channels (un-‐gated ion channels) ii. voltage-‐gated potassium ion channel iii. voltage-‐gated sodium ion channel iv. voltage-‐gated calcium ion channel v. sodium potassium pump
- Which structure(s) is/are responsible for maintaining the resting potential? a) only i b) only iii c) both i and iii d) both i and v e) both ii and iii
- Stage D is the __________ stage and during this stage the ________ are open. a) depolarization : iii b) depolarization : ii c) repolarization : v d) repolarization : ii e) undershoot : ii
- You could make the positive voltage peak of the action potential lower by: a) blocking iii. b) blocking iv. c) closing the deactivation gate of iii at a slower rate. d) closing the iii at a faster rate. e) None of the above would change the peak of the action potential.
- To prevent the undershoot stage (D) the _________ would have to close at a ______ rate. a) ii : faster b) ii : slower c) iii : faster d) iii: slower 5 ) If the axon was at resting potential, what would happen if you blocked all the sodium-‐potassium pumps, but left the leak channels open? a) The membrane potential would become more positive. b) The membrane potential would become more negative. c) The membrane potential would stay the same. 6 ) What if you engineered a neuron with a voltage-‐gated calcium channel that stayed open longer than a typical neuron. Compared to a typical neuron, how would this engineered neuron’s action potential differ. a) It would have a higher resting potential. b) It would be the same. c) It would have a lower undershoot. d) It would have a higher peak positive voltage.
10 ) A mutation of a regulator gene decreases the production of negatively charged macromolecules inside a nerve cell. What effect would this have on the ability of the cell to propagate an action potential? a) It would make the resting potential of the cell more positive and increase the likelihood that the neuron would fire. b) It would have no effect on the resting potential of the cell, but it would make the sodium channels less likely to open and therefore decrease the likelihood that a neuron would fire. c) It would hyperpolarize the cell and make it more likely to fire. d) It would hyperpolarize the cell and make it less likely to fire. 11 ) Which of the following manipulations would reduce the release of neurotransmitter from a presynaptic neuron terminal? a) A reduction in extracellular calcium ion concentration at the axon terminal b) An increase in extracellular chloride ion concentration at the axon terminal c) Both of the above manipulations would reduce the release of neurotransmitter. d) Neither of the above manipulations would reduce the release of neurotransmitter. 12 ) What is the evidence that hemoglobin was no longer necessary for ice fish to transport oxygen to their body tissues? a) The presence of antifreeze proteins in their blood. b) The translucent color of their flesh. c) The lose and degradation of the genes responsible for the globin part of hemoglobin. d) The evolution of protolungs that they use to gulp air. 13 ) What does it mean to say an animal is a homeothermic endotherm? a) Its body temperature can vary, but it produces it own heat. b) Its body temperature varies because it gets heat from sources outside its body. c) Its body temperature does not vary and it produces it own heat. d) its body temperature does not vary and it gets most of its heat from outside its body. 14 ) Which is not an adaptation of Ice fish to the increase the exchange of oxygen in cold water? a) The lose of scales and increase in capillary size in the skin. b) The lose of the ability to produce hemoglobin. c) The evolution of a larger heart. d) The evolution of increased gill surface area.
15 ) From the list below, what advantage(s) does an endothermic animal have over an ectothermic animal? i)enzymes at optimal temperature at all times ii) greater proportion of energy goes to reproduction iii) must obtain large quantities of energy-‐rich food. iv) can remain active in winter v) can sustain very high levels of aerobic activities like running and flying vi) more vulnerable to predation in cold weather vii) able to thrive with much lower food intake viii) muscular activity and digestion slow down as body temperature drops a)i, iii, and iv b)i, viii, and v c)i, iv, and v d)ii, vii, viii e)ii and vii 16 ) If the body’s internal temperature is higher than the set point, which of the following responses are likely to be triggered? i) sweating ii) constriction of capillaries near the surface of the skin iii) increased breathing rate iv) increase in cellular metabolism throughout the body v) muscle shivering vi) dilation of capillaries near the surface of the skin a) i, iii, and v b) iv and v and ii c) i, iii, and vi d) iii, iv, and vi 17 ) The concentrations of ions inside and outside a nerve cell are maintained at asymmetric levels due to: a) osmosis b) diffusion c) sodium-‐potassium pumps d) symports and antiports 18 ) Certain species of fish, frogs, newts, snails, and crabs all have tetrodotoxin (a powerful neurotoxin) in some part(s) of their bodies. How does it get there? a) They all synthesize it. b) They all get it from their diet by ingesting certain bacteria. c) They all get it from their diet by ingesting certain plants. d) none of the above.
23 ) Wading birds in northern climates are able to walk in pools of cold water and on ice without dying of hypothermia because they have countercurrent heat exchangers in their legs. These exchangers allow heat in warm blood going to the feet to be transferred to cool blood returning from the feet. Why are such countercurrent heat exchangers so efficient at conserving heat? a) The gradient between the two currents is maintained even as one current cools and the other current heats. b) There is a large temperature differential from one end of each current to the other. c) Blood in the arteries and veins flow in the same direction, so there is no loss to friction. d) All of the above e) A and B only The following statement applies to questions 24 to 26. When a mutation changes the sequence of nucleotides which of the following effects can it have? 24 ) The mutation can create a new gene that confers an advantage on its bearer. a) True b) False 25 ) The mutation can create a new gene that confers a disadvantage on its bearer. a) True b) False 26 ) The mutation can have no effect on the gene and the mutation’s effect would be neutral. The above question is dropped from the exam 26 ) What would happen if body temperature were controlled by a positive feedback system? a) More effectors would be needed to maintain the set point. b) Different integrators would be needed to maintain the set point. c) The body temperature would increasingly move away from the set point and result in death. d) The body temperature would be maintained much closer to the set point, relieving the stress to the animal. 27 ) What is the name of the gap between two schwann cells? a) Node of Xavier b) Node of Ranvier c) Gap of myelination d) myelination disjunction
- If the sodium potassium pump functioned at a slower than normal rate: a) It would decrease the amount of time before a neuron could fire again. b) It would increase the amount of time before the neuron could fire again. c) It would shorten the duration of the undershoot stage of an action potential. d) both a and c are correct e) both b and c are correct
- The method used to determine the function of ion channels is called a) amperometry b) patch-‐clamp c) electromyography d) membrane potentiometry e) none of the above
- In the evolution of the neuron what conditions would have likely evolved first? ii – bi-‐directional conduction iii – electrical synapses iv – chemical synapses v – un-‐gated ion channels vi – gated ion channels a) i, iii, vi b) ii, iii, v c) i, iv, v d) i, iii, v e) none of the above
- The equivalent of a schwann cell in the central nervous system is a a) oligodendrocyte b) astrocycte c) type II schwann cell d) glial cell e) hair cell
- When Dr. Houlihan spent time at high altitude in Colorado his body _____ to the lower levels of oxygen. a) adapted b) assimilated c) compensated d) regulated e) acclimated
- Extra Credit What type of biology does Carroll, the author of “Making of the fittest”, study? a) Evo-‐Devo, Evolutionary Developmental Biology b) Evo-‐Eco, Ecological Evolutionary Biology c) Evolutionary Physiology
